SUDBURY — It only took a few seconds for Dave Walter of Hudson on Saturday afternoon to launch his sailplane, a small Styrofoam plane that glides through the air.

"Make it a good one," said Bruce Schneider, also of Hudson.

With little notice, the electric-powered winches launched his plane to a couple hundred feet in the air. There are no engines on the planes only radio controlled elevators and rudders.

Walter, who has been flying gliders since 1986, was one of 18 entrants in a sailplane contest at Davis Field off North Road. There were two groups - planes with wingspan less than 2 meters, and unlimited.

"Keeping the plane in the air is the challenge," he said. "Gliders are always falling relative to the air. The only way they’ll go up is if the air is going up."

The goal is to stay in the air for a set amount of time without going over under. There is also a target to hit as you land for extra points.

During Walter’s launch, the goal was seven minutes.

"I still couldn’t get seven minutes," Walter said to the other contestants. He made it six minutes and 18 seconds.

Chris Schuch of Stow wasn’t as lucky.

"I made it like two minutes and 50-something seconds," he said. "Not very good."

The hobby is all about catching rising air currents (known as thermals) — like a bird.

"It is a hobby of skill," Schuch said. "You have to control the plane. You have to find the thermals. You have to stay in the thermals. And you have to land in the right place at the right time."

The event was run by Charles River Radio Controllers club.

Contest Director Tracy Clark said there was a good turnout.

"It was a little breezier than we expected," he said. "It was a bit more of a challenge, but a good day. It is not like we didn’t have lift."

Much of the event is about socializing and bragging rights, he said.

"It was designed to be a fun contest," said David Spielman, president of the club.

Jonathan Phelps can be reached at 508-626-4338 or jphelps@wickedlocal.com. Follow him on Twitter @JPhelps_MW.